1. Field of the Invention
The present invention relates to a digital broadcast receiver, and more particularly, to a channel scanning method in which channel scanning is efficiently carried out in a digital broadcast receiver having a plurality of tuners.
2. Description of the Related Art
A digital broadcast receiver is an apparatus that restores original digital data from a transmitted broadcast signal according to a digital transmission scheme. A digital broadcast transmitter (i.e., a broadcast station area, hereinafter, referred to as a head end) converts an analog signal into a digital signal comprised of 0s and 1s using digital technology, compresses the converted signal together with other information, and then transmits the compressed signal according to a digital transmission scheme. Then, the digital broadcast receiver receives and converts the transmitted signal into the original video and audio.
Compared to analog technology, digital technology is usually less effected by noise, needs less transmission power, allows for error correction, and suffers less degradation in transmission, copying, and storing. In addition, digital technology enables high band compression of an audio/video signal, and it facilitates searching, processing, and editing of information. Digital broadcasts are advantageous in that they are less effected by noise and can be efficiently transmitted compared to conventional analog TV broadcasts.
Currently, digital broadcast receiver programs provide a plurality of broadcast channels received from a variety of sources, such as terrestrial, satellite, and cable broadcasters. However, the number of broadcast channels provided by digital broadcast receivers is expected to increase considerably, thus making it more difficult for users to find out what broadcast channels are offered or what programs the input broadcast signals contain. Accordingly, various methods for helping users to select a channel efficiently or a broadcast program through an electronic program guide (EPG) or channel scanning have been suggested.
One of the various methods is a channel scanning method, which is also called an auto-programming method. In the channel scanning method, it is determined whether a broadcast signal exists in each of a plurality of channels constituting an entire range of channels provided by a tuner of a digital broadcast receiver by checking every channel. If a predetermined channel is determined to have a broadcast signal, information regarding the broadcast signal is stored in conjunction with the channel number. Otherwise, it is determined whether the next channel (particularly, a channel directly above the predetermined channel) has a broadcast signal.
Recently, digital broadcast receivers, which include a plurality of tuners or a plurality of pairs of tuners/demodulators to provide a picture-in-picture (PIP) function and a quick channel switch function, have been developed. In order to meet various demands of users, an increasing number of digital broadcast receivers are expected to be manufactured having a plurality of tuners.
To date, conventional digital broadcast receivers, however, scan channels using only one tuner at a time, even though they may include a plurality of tuners, and thus, they are not making full use of their capabilities. In view of the above, there is still a need to develop an efficient technique of scanning channels by simultaneously using a plurality of tuners in a digital broadcast receiver.